Article of manufacture and method for making same



Patented May 4, 1937 UNITED STATES PATENT ()FFH ARTICLE OF MANUFACTUREAND METHOD.

FOR MAKING SAlWE Delaware No Drawing. Application September 1, 1934,

Serial No. 742,473'

8 Claims.

This invention relates to the art of stainprevention, and, inparticular, it pertains to the manufacture of regenerated cellulose capsand bands which resist staining when dried in place over bottle tops andthe like.

Cellulosic bottle caps and bands, and in particular bottle caps andbands of regenerated cellulose, are now used on a large commercialscale. These caps andbands are applied to arbottle while they are stillin a gel state, i. e. after coagulation and regeneration but beforebeing dried, and are permitted to shrink in place by drying, therebyfitting tightly over and thus forming a seal for the bottle caps andbands. It has long been known, however, that when the gel caps or bandsare dried downover cork stoppers or over closures comprising iron oralloys containing iron, the pellicles tend to become stained, and thiscondition seriously impairs the utility and salability of the caps andbands, particularly where the pellicles contain opaquing materials suchas titanium oxide or other pigments.

An object of the invention pertains to the production of cellulosicpellicles which resist staining. A further object of the inventionrelates to the prevention of staining of bottle caps,

l bands and the like, when applied in the wet state to bottles and arepermitted to shrink and dry in place, in contact with cork, iron or thelike.

Other objects of the invention will appear here- .inafter.

It is believed that the staining of pellicles of regenerated celluloseand the like which are applied in the gel state and are permitted toshrink and dry in place over cork is due to the absorption of tannin,tannic acid and other related organic materials which are present insubstantial amounts in cork. Iron stains are believed to arise from thefact that soluble compounds of iron are absorbed into and through thebody of the caps or bands during the setting i thereof, that is to say,while the pellicles are being dried. In accordance with the presentinvention, in order to overcome the tendency towards stains, thepellicles are treated with an aqueous solution of a compound of thecharacter specifically described hereinafter which dimin ishes orcompletely inhibits staining from cork or iron.

It is customary to ship gel regenerated cellulose bottle caps or bandsin a dilute aqueous glycerin solution, the glycerin acting as asoftener. The pellicles may be placed in the shipping container and thetreating solution, containing the desired amount of glycerin and ofstain inhibitor, is

then poured in until it covers the caps or bands, after which thecontainer may be closed and shipped and the treated caps, wheneverdesired, placed on the bottles or like vessels and permitted to dry andshrink over the tops of the bottles. The caps or hands immersed in theshipping, solution soon come to equilibrium with the solu-- tion afterabsorption of a certain amount of the glycerin and of the stainpreventing agent.

It has been discovered in accordance with this, invention that sodiumaluminate, even in very small concentrations, imparts to the gelpellicles of regenerated cellulose a highly satisfactory resistance tostaining.

The following example illustrates one mode of applying the principles ofthe invention:

A concentrated solution of sodium aluminate is prepared by adding 25grams of solid NaOH to grams of an aqueous solution containing 50% byweight of A1(NO3)3.9H2O. A shipping container is filled with caps orbands of gel regenerated cellulose pellicles which have been given theirfinal washing in soft water, and there is then added to the container,in an amount sufiicient tocover the pellicles, an aqueous solutioncontaining the sodium aluminate solution diluted so that the solution,after reaching equilibrium with the pellicles, contains 1% aluminumnitrate and 0.5% caustic. Suflicient glycerine is added to yield about6% glycerine in the equilibrium solution. The container may then besealed and shipped tothe desired point, the pellicles being withdrawnwhen desired, the excess solution shaken ofi, the pellicles placed overthe bottles, and shrunk in place. The dried pellicles applied eitherover cork stoppers or over iron, and dried, exhibit no appreciablestaining.v

It has been further observed that when dyed caps are placed in ashipping solution of sodium aluminate, such as has been described, nosubstantial bleeding of the dye takes place, and no changes in the shadeof the dyed caps could be observed after soaking in the solution for aweek.

Care should be taken so that the sodium aluminate solution will notcontain too much caustic. While the solutions need not be prepared withanalytical precision, it has been found that sodium aluminate solutionscontaining 1% aluminum nitrate (calculated as A1(NO3)3.9H20) and 0.5% to0.8% sodium hydroxide, have been found satisfactory to prevent theformation of either cork stains or iron stains. When using sodiumaluminate having the proportion of aluminum nitrate to sodium hydroxideapproximately within the ranges just given, the shipping solution maycontain from a small fraction of a percent by weight upwardly of sodiumaluminate although it is preferred that the amount used be between 0.5%and 5% sodium aluminate in the equilibrium solution.

While sodium aluminate represents the preferred form of the inventionthe invention contemplates the use of other water-soluble salts ofaluminum, for example, potassium aluminate, similarly prepared. Insteadof using aluminum nitrate as the source of the aluminum for reactingwith caustic, other soluble aluminum salts may be used. Thus, a 0.64% byweight aqueous solution of A12S04.18H2O respectively were prepared and0.5% by weight sodium hydroxide aqueous solution was added to yield asodium aluminate solution equivalent to that referred to in the aboveexample. These were effective in the same way, for the prevention ofcork stains and of iron stains, as the sodium aluminate solutionsprepared from aluminum nitrate.

Although the invention is of particular benefit when applied toregenerated cellulose pellicles prepared by the viscose process, it willbe understood that it may be similarly applied to regenerated cellulosepellicles prepared from cuprammonium cellulose solution as well as fromviscose, or it may be applied also to pellicles composed of othercellulosic materials prepared by Wet-casting methods, for example,cellulose esters such as cellulose acetate, and cellulose ethers such asglycol cellulose or ethyl cellulose.

While the invention is preferably applied to gel pellicles, it will beunderstood that the scope of the invention includes the treatment ofpellicles which have been dried and then rewetted prior to treatment.

Moreover, it is to be understood that instead of shipping pellicles in ashipping solution, they may of course be removed from a shippingsolution which has attained equilibrium, and shipped in a moistcondition to the point of use.

Any variation or modification of the invention as described, whichconforms to the spirit of the invention is intended to be includedwithin the scope of the claims.

I claim:

1. The method of preventing the staining of regenerated cellulosepellicles, which comprises the step of incorporating in said pellicles acolorless water-soluble aluminate by absorption from an aqueous solutionof said aluminate.

2. The method of preventing the staining of regenerated cellulosepellicles, which comprises the step of incorporating in said pelliclesof sodium aluminate by absorption from an aqueous solution of saidaluminate.

3. A pellicle of non-fibrous cellulosic material cast from an aqueoussolution, said pellicle having incorporated therein a substantialquantity of a colorless, water-soluble aluminate, the said pelliclebeing characterized by its resistance to staining when placed in contactwith iron or cork.

4. A pellicle of regenerated cellulose having incorporated therein asubstantial quantity of a colorless, Water-soluble aluminate, saidpellicle being characterized by its resistance to staining when placedin contact with cork.

5. A pellicle of non-fibrous cellulosic material cast from an aqueoussolution, said pellicle having incorporated therein a substantialquantity of sodium aluminate, the said pellicle being characterized byits resistance to staining when placed in contact With iron or cork.

6. The method of preventing the staining of non-fibrous cellulosicpellicles cast from an aqueous solution, which comprises the step ofincorporating in said pellicles a colorless, watersoluble aluminate byabsorption from an aqueous solution of said aluminate.

7. The method of preventing the staining of non-fibrous cellulosicpellicles cast from an aqueous solution, which comprises the step ofincorporating in said pellicles sodium aluminate by absorption from anaqueous solution of said aluminate having present a slight excess ofcaustic soda.

8. A pellicle of regenerated cellulose having incorporated therein asubstantial quantity of so dium aluminate, such pellicle beingcharacterized by its resistance to staining when placed in' contact withiron or cork.

ALBERT HERSHBERGER.

